Understanding Eurasian Watermilfoil
John D. Madsen Geosystems Research Institute Mississippi State University [email protected]
Cultus & Nicola Lakes Water Quality & Eurasian Watermilfoil Workshop, Fraser Basin Council, Abbottsford, BC, Canada February 15, 2013 www.gri.msstate.edu Eurasian watermilfoil Overview • Taxonomy and description • Distribution • Habitat • Ecological range • Problems • Propagation and spread • Growth and phenology
www.gri.msstate.edu Benefits of Aquatic Plants • Stabilize lakes sediments, reducing resuspension • Increase sedimentation, reducing turbidity • Provide habitat for insects, forage fish, fish spawning and YOY fish • Provide food for waterfowl, other animals www.gri.msstate.edu Invasive vs. Native Community
Invasive Myriophyllum spicatum
Native Potamogeton sp. Mixed stand
www.gri.msstate.edu Eurasian watermilfoil
• Myriophyllum spicatum L. • Aquatic family Haloragaceae • Forms dense nuisance surface canopy • Herbaceous evergreen perennial • Spreads by root crown / runner and autofragment • Nonnative from Europe and Asia www.gri.msstate.edu Eurasian watermilfoil Problems
• Nuisance growth interfering with recreation • Human use impacts • Ecosystem impacts
www.gri.msstate.edu Human Use Impacts of Eurasian watermilfoil
• Commercial Navigation • Hydropower • Flood Control • Spread of insect- borne diseases • Recreational impairment • Property value • Human health www.gri.msstate.edu Ecological Effects of Eurasian watermilfoil
•Degradation of water quality •Reduction in species diversity •Suppresses native plant species •Potential impacts on endangered species •Alters animal communities www.gri.msstate.edu Fall River, CA Hennepin Lake, IL
Pend Oreille River, WA
Mobile Bay, AL www.gri.msstate.edu Lake Minnetonka, MN Lake Hortonia, VT
Houghton Lake, MI Waneta Lake, NY Remetrix, Inc.
www.gri.msstate.edu Taxonomy • Wholly-aquatic family Haloragaceae • Two genera – Myriophyllum and Proserpinaca • Fourteen Myriophyllum species in the US, twelve are native • Four native species are shown for western North Myriophyllum spicatum America in Vermont • Two invasive species www.gri.msstate.edu Taxonomy of Myriophyllum
• Despite fifty years of work on Eurasian watermilfoil in North America, there are persistent concerns and confusion, even among professionals, on how to tell Eurasian watermilfoil from native watermilfoil species (particularly northern watermilfoil). • Recent genetic evidence of hybridization further exacerbates the confusion www.gri.msstate.edu Myriophyllum species in the US Scientific Name Common Name Native or Nonnative Myriophyllum alterniflorum DC Alternate flower watermifloil Native Myriophyllum aquaticum (Vell.) Verdc. Parrotfeather Nonnative Myriophyllum farwellii Morong Farwell’s watermilfoil Native Myriophyllum heterophyllum Michx. Variableleaf watermilfoil Native* Myriophyllum hippuroides Nutt. ex Western watermilfoil Native Torr. & A. Gray Myriophyllum humile (Raf.) Morong Low watermilfoil Native Myriophyllum laxum Shuttlw. ex Loose watermilfoil Native Chapm. Myriophyllum pinnatum (Walter) Cutleaf watermilfoil Native Britton, Sterns & Poggenb. Myriophyllum quitense Kunth. Andean watermilfoil Native Myriophyllum sibiricum Komarov Northern watermilfoil Native Myriophyllum spicatum L. Eurasian watermilfoil Nonnative Myriophyllum tenellum Bigelow Slender watermilfoil Native Myriophyllum ussuriense (Regel) Russian watermilfoil Native Maxim. Myriophyllum verticillatum L. Whorl-leaf watermilfoil Native
Native Myriophyllum
Western Watermilfoil Myriophyllum hippuroides Kathy Hamel
Andian Watermilfoil Myriophyllum quitense Jenifer Parsons
Northern Watermilfoil Myriophyllum sibiricum John Madsen
Whorled watermilfoil Myriophyllum verticillatum USDA NRCS Northern watermilfoil
Myriophyllum sibiricum Komarov Common native in northern United States Occasionally forms a nuisance Circumboreal www.gri.msstate.edu Eurasian watermilfoil • Myriophyllum spicatum L. • Nonnative from Eurasia • Widespread nuisance-forming invasive (49 US states, southern tier provinces of Canada) www.gri.msstate.edu Morphological Methods • Morphological conditions measured in six segments of each specimen: • Stem red or green • Apical meristem rounded or flat • Leaf tips rounded or flat • Internode length Northern watermilfoil • Stem thickness • Leaf length specimen from Pend • Leaflet length Oreille Lake, ID • Leaflet number www.gri.msstate.edu Genetic Methods
• PCR Amplification separated by electrophoresis and sequenced (BGU) • Phylogenetic analysis and chloroplast gene sequencing (GVSU) • PCR-RFLP (MSU) • All three labs used different approaches, with some cross-over verification www.gri.msstate.edu Morphological Results
Comparison of Boolean characteristics of northern watermilfoil and Eurasian watermilfoil, with a comparison by Fisher's exact test. Fisher's Exact Test Characteristic Northern watermilfoil Eurasian watermilfoil P-value
Flat Leaf End No Yes No Yes 4.2% 5.6% 95.8% (23) 94.4% (17) <0.0001 (1) (1)
Flat Apical Meristem No Yes No Yes 5.6% 83.3% (20) 16.7% (4) 94.4% (17) <0.001 (1)
Stem Color Green Red Green Red 27.8% 87.5% (21) 12.5% (3) 72.2% (13) 0.256 (5) Morphological Results, cont.
Comparison of morphological characteristics of northern watermilfoil and Eurasian watermilfoil, with a comparison by T-test
Northern watermilfoil Eurasian watermilfoil T-test Variable Mean SE Mean Mean SE Mean p-value Leaflet Number 8.10 0.123 16.32 0.253 <0.0001 Leaf Length (mm) 20.0 0.420 18.07 0.415 0.001 Leaflet Length (mm) 13.8 0.438 8.556 0.244 <0.0001 Stem thickness (mm) 1.03 0.015 1.056 0.022 0.44 Internode Length (mm) 15.6 0.916 13.06 0.701 0.0256 www.gri.msstate.edu Northern Eurasian
Frequency of number of leaflet pairs per leaf for northern watermilfoil (SIB, left) and Eurasian watermilfoil (SPI, right). Northern Watermilfoil (Myriophyllum sibiricum)
. Native submersed aquatic plant . Leaves arranged in whorls of 4 around stem, typically remains rigid when removed from water . Leaves have < 12 leaflet pairs . Leaf tips are round not flat . Reproduces by stem fragments and turions . Northern watermilfoil often has longer leaves than Eurasian watermilfoil . ID Characteristics: Round leaf tips and < 12 leaflet pairs Eurasian Watermilfoil (Myriophyllum spicatum)
. Introduced from Europe . Submersed evergreen perennial . Spreads by root crowns, runners, and fragments . Grows in 2 to 15 feet of water, forms surface canopy . Leaves are in whorls of 4 around stem . ID Characteristics: Flat leaf ends, Flat apical meristem, > 12 leaflet pairs
Genetic Analysis Findings • All three labs agree that plants identified as northern watermilfoil were northern watermilfoil • All three labs agree that plants identified as Eurasian watermilfoil were Eurasian watermilfoil • No evidence of hybridization in any samples
www.gri.msstate.edu Eurasian watermilfoil Gets More Complicated…
• Hybridization with M. sibiricum • May form a terrestrial form on moist soil and mud flats
www.gri.msstate.edu Habitat • Lakes, rivers, reservoirs, ponds, freshwater and brackish estuaries • Low to moderate organic content in sediment • Fine clay to sand, cobble, and rock crevices in sediment • Quiet to high energy zone, rooting below wave wash zone
www.gri.msstate.edu What do plants need?
Light Water Carbon dioxide
Oxygen
Water Nutrients: Nitrogen Phosphorus A Tale of Two Plants
CO2, O2 Nutrients Water Removal of Toxic Gases Emergent, Floating Submersed Requirements for Growth
Light Water attenuates amount of available light, controls depth distribution and growth rate Nutrients For both types of plants, sediment is bulk of source for major limiting nutrients (N, P) of rooted plants Water You’re kidding, right? Carbon dioxide Gases diffuse 1,000x more slowly in water, rate of availability limits photosynthesis Oxygen Oxygen may be low for respiration, particularly in roots Temperature/Heat As with all plants, temperature range may limit growth Toxic gases in sediment (methane, sulfate) Floating, emergent plants have a “flow-through” system for gas exchange A safe place to root Disturbance, water level fluctuation, herbivory may limit growth Comparison between Eurasian watermilfoil and Native Pondweed - Photosynthesis
Submersed plant photosynthesis is controlled by light levels
Madsen and Boylen 1988 www.gri.msstate.edu Maximum depth of colonization versus light transparency
Canfield et al. 1985
Maximum depth of plant growth is largely controlled by light availability
www.gri.msstate.edu Plant Nutrition
Source of Nutrients Water column Sediment Growth-dilution
www.gri.msstate.edu Nutrient Sources: Sediment vs. Water
Barko et al. 1991 www.gri.msstate.edu Tissue Concentrations of N and P
As the plants grow, nutrient uptake does not keep up with the increasing volume or biomass of the plant resulting in “growth dilution” of nutrient content in the plants. If growth continues, nutrient Madsen limitation will 1991 eventually occur. www.gri.msstate.edu Phosphorus and Algae
Dillon and Rigler 1974. Limnology and Oceanography Vol. 19, No. 5, 767-773. Increased phosphorus in water leads to more algal growth While some increased algal growth will benefit fish production, too much algae leads to oxygen depletion, fish kills, and odor problems Nutrients will also increase growth of free-floating plants This is Your Lake on Phosphorus:
Excessive planktonic and filamentous algae or duckweed is directly related to fertilizing ponds Bicarbonate Uptake Many submersed plants can use bicarbonate as well as dissolved carbon dioxide for photosynthesis. Bicarbonate and carbon dioxide together are known as dissolved inorganic carbon, or DIC
Stevenson 1988. Limnol. Oceanogr. 33:867-893. Inorganic Carbon vs. Photosynthesis
Adams et al. 1978. Limnol. Oceanogr. 23:912-919. EWM versus Trophic Status:
Smith and Barko 1990
Relative Abundance Relative
Oligotrophic Eutrophic www.gri.msstate.edu Plant Response to the Environment
Approximate
Boundary Plant Abundance Plant
Environmental Gradient www.gri.msstate.edu EWM Abundance vs. Total Phosphorus 100
80
60
40
Milfoil Abundance Milfoil 20
0 020 40 60 80100120140160180200 Total Phosphorus (g L-1) EWM Abundance by Trophic Index 100
80
60
40
Milfoil Abundance Milfoil 20
0 05101520253035404550556065707580 Trophic Index EWM Abundance and Alkalinity
www.gri.msstate.edu Salinity and Water Chemistry
• Up to 33% seawater • Softwater to hardwater
www.gri.msstate.edu Nichols and Buchan 1997. JAPM Ecological Impacts
• Reduces oxygen in water beneath canopy • Increases internal nutrient loading, phosphorus • Shades native plants • Alters predator/prey balance
www.gri.msstate.edu Eurasian watermilfoil vs. Native Plants
Why does Eurasian watermilfoil suppress native plants? •Various mechanisms have been proposed, including: –Ability to use bicarbonate as a photosynthetic carbon source –Photosynthetic adaptations –High productivity
www.gri.msstate.edu Canopy Formation Vmax vs Km
Madsen Madsen et 1991 al. Light Compensation Point vs Km
Madsen Madsen et 1991 al. Daily Carbon Balance, Open Water
Madsen et al. 1991 Daily Carbon Balance, Milfoil Canopy
Madsen et al. 1991 Invasive Plants and Fish • Alter predator/prey balance • After time, produces large numbers of stunted, underfed fish • Valued by fisherman, not fisheries biologists • Concern (though no data) that predatory fish hide in wait in dense vegetation for salmonids www.gri.msstate.edu Aquatic Plants and Predator/Prey Balance
Largemouth Bass
Sunfish
Production Relative Fish
Percent Plant Cover www.gri.msstate.edu Is this reversible? Does Management do any Good? Since shading is the main mechanism of competition, it is an elastic change – and reversible With some management techniques, native plants already present respond positively in year of treatment With less selective techniques, sufficient plant propagules exist for revegetation www.gri.msstate.edu Selective Management with Herbicides
Untreated mesocosm Mesocosm treated with Triclopyr www.gri.msstate.edu www.gri.msstate.edu Restoration from Benthic Barrier
Eichler et al. 1995. JAPM 33:51-54.
www.gri.msstate.edu Native Plant Restoration from Suction Dredging
Eichler et al. 1993. JAPM 31:144-148.
www.gri.msstate.edu Four Life History Types •Annual –Overwinters by seed Seed only •Herbaceous perennial Tuber – –Overwinters by a vegetative vegetative propagule propagule •Evergreen Perennial –Overwinters by green shoot Root Crown – evergreen •Woody perennial perennial –Overwinters as a woody stem –Rare in aquatic sites www.gri.msstate.edu Propagation and Spread
• Reproduction by seed • Reproduction by vegetative means • Spread by natural causes • Spread by humans
www.gri.msstate.edu Propagation • Seed – Seed set and success • Vegetative – Autofragment – Root Crown – Rhizomes – Runners www.gri.msstate.edu Seed Set Eutrophic lakes produce more flowers and higher percentage of seed set than oligotrophic lakes
Madsen and Boylen 1989
www.gri.msstate.edu Seed Germination and Environment
Madsen et al. 1988
www.gri.msstate.edu In Situ Seed Germination Madsen et al 1988
www.gri.msstate.edu Seed Germination and Burial
www.gri.msstate.edu Drying Period and Seed Germination
Eurasian watermilfoil seeds tolerate long periods of drying
Hartleb and Madsen 1997 www.gri.msstate.edu Propagation by Seed
•Large number of seeds are produced by Eurasian watermilfoil •Seeds are viable, and germinate underwater •Few, if any, seedlings survive to maturity underwater •Seed propagation not important in most lakes www.gri.msstate.edu Vegetative Spread Fragments
Runner
Rhizome
www.gri.msstate.edu VT DEC Vegetative Propagation: Runners
•Eurasian watermilfoil overwinters as root crowns – a tight mass of growing stems •Underground stems may produce new root crowns •Erect stem can fall over and form new root crown
www.gri.msstate.edu Vegetative Propagation: Fragments
• Autofragments formed by plant tend to predominate • Allofragments from breakage may also be viable • Autofragment production is greatest late in summer • Autofragments may overwinter
www.gri.msstate.edu Northern Asexual Spread
Peak rhizome spread in August, peak autofragment formation in September
Madsen et al. 1988
www.gri.msstate.edu •Southern population vegetative spread follows a different pattern based on environmental parameters •Colony expanded at rate of 3.8 cm / day
Madsen and Smith 1997 www.gri.msstate.edu Invasion Process
Introduction
Colony Formation
Establishment www.gri.msstate.edu Spread of Melaleuca
Campbell, F.T. 1997. In: J.O. Luken and J.W. Thierot, Assessment and Management of Plant Invasions. Springer, New York Spread of Melaleuca
Campbell, F.T. 1997. In: J.O. Luken and J.W. Thierot, Assessment and Management of Plant Invasions. Springer, New York Spread of Invasive Plants over Time
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770. Cost of Control vs Time of Inter- vention
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770. Phases of Inva- sion vs Manage -ment Priority
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770. www.gri.msstate.edu “Natural” Dispersal
• Water movement – Wave action – Currents – Tides • Animal carriers
www.gri.msstate.edu Boat Launches • Boats are the #1 mode of Eurasian watermilfoil spread in North America • Boat launches are the most common site for first infestations in a new lake
www.gri.msstate.edu Where to Check on Boats and Trailers
www.gri.msstate.eduMN DNR Prevention
•Educational signs at boat launches, marinas •Volunteer “inspectors” to teach on EWM danger •Volunteer Plant Survey to watch for EWM in lake •Target boat launches! •Boats can be cleaned manually without any special equipment
www.gri.msstate.edu Phenology and Growth • Eurasian watermilfoil is an evergreen perennial • Annual growth cycle varies across country • Storage of carbohydrates is key
www.gri.msstate.edu Temperature, Light and Growth
500 Warm, Clear Year Cool, Cloudy Year 400
)
-2
300
200
Biomass (g DW m Biomass (g DW 100
0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 500
) -2 400 Cold Water North Temperate
300 •Eurasian 200 100 watermilfoil Biomass (g DW m 0 phenology J F M A M J J A S O N D varies 500
)
-2 Warm Water North Temperate geograph- 400 ically, 300 inter- 200 annually, 100
Biomass (g DW m and 0 J F M A M J J A S O N D between 450
) lakes -2 400 350 300 250 200 150 Warm Water South Temperate
Biomass (g DW m 100 J F M A M J J A S O N D Carbohydrate Allocation
Owens and Madsen 1998 Seasonal Carbohydrate Allocation
Owens and Madsen 1998
Carbohydrate Low Point
Low Point
Total Nonstructural Nonstructural Total Carbohydrate Content Content Carbohydrate
Month of the Year
www.gri.msstate.edu Carbohydrate: TNC storage by season
www.gri.msstate.edu Low Points in Carbohydrate Storage of
Eurasian watermilfoil Madsen 1997 •Low carbohydrate storage in summer through fall in southern populations of Eurasian watermilfoil •Northern populations usually have a distinct low point in early to mid summer www.gri.msstate.edu Eurasian watermilfoil Carbohydrate Low Points
5
Northern Sites Southern Sites 4
3
2
Frequency of Studies of Frequency
1
0 Madsen 1997 A M J J A S O Month of Year www.gri.msstate.edu Autofragment Formation
•Plant produces stem segments through abscission layer formation •Timing is typically in fall, in both north and south
Madsen et al. 1988 www.gri.msstate.edu Eurasian watermilfoil Management Application
•Timing of management to coincide with low point •Timing of management to prevent autofragment formation •Drawdown exploits lack of resistant propagule
www.gri.msstate.edu Conclusion
Management goal is maintenance of low invasive plant population with diverse native plant community at most economical cost
Before management of invasive plant After management of invasive plant
www.gri.msstate.edu Dr. John D. Madsen Mississippi State University Geosystems Research Institute Box 9627 Mississippi State, MS 39762-9627 Ph. 662-325-2428 Fax 662-325-7692 E-mail: [email protected]
www.gri.msstate.edu